[boost] graph visitor interface simplification

From: jsiek_at_[hidden]
Date: 2000-01-27 01:19:52

I think I've got a good solution for simplifying visitors.
Instead of using inheritance to compose them, we could use
a compile-time list. Like this:

Cons<V1, Cons<V2, Nil> >

Then inside the algorithms, it will run through the list and
call process() for each visitor in the list.

Of course, the user doesn't want to see Cons<...>, so
we provide helpers for creating them, could even overload "+"
for this purpose. Then you could write:

depth_first_search(..., v1 + v2 + v3);

Ciao,

Jeremy